MIPS: Loongson: cs5536_pci: Add a missing include

Add a missing include to get rid of the following sparse warnings:
warning: symbol 'cs5536_pci_conf_write4' was not declared. Should it be static?
warning: symbol 'cs5536_pci_conf_read4' was not declared. Should it be static?
Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/8526/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/loongson/common/cs5536/cs5536_pci.c

@@ -21,6 +21,7 @@
  */
 
 #include <linux/types.h>
+#include <cs5536/cs5536_pci.h>
 #include <cs5536/cs5536_vsm.h>
 
 enum {